Fractionation of RBCs via label-free magnetophoresis using novel additive-manufactured devices - SUMMARY Blood cell fractionation using magnetic fields is a promising technology capable of achieving the separation and analysis of blood cells simultaneously, which is essential in clinical diagnosis and can provide insight into important cellular processes that might not be able to be observed easily with other techniques. For example, our previous studies on the analysis of red blood cells (RBCs) using single-cell magnetometry have reported that specific fractions of cells have a low magnetic susceptibility and hemoglobin (Hb) concentration, which is related to the maturity of the cells in circulation as well as a predictor of ex vivo cell aging. Label-free magnetophoresis has also been able to determine that, during the approved 6-week storage period of RBC units in blood banks, the cells lose a significant amount of magnetic susceptibility and iron concentration. Thus, label-free magnetic fractionation can be exploited to separate the healthy, Hb-enriched cells from the damaged and iron-deficient cells in RBC units, in order to extend their shelf life, and to ensure a better utilization of the limited resources we currently have. Also, magnetic fractionation could be used to design novel transfusion therapies that can alleviate the negative effects that patients requiring repeated RBC exchange transfusions suffer, since this technique can be employed to discard detrimental RBCs with low/abnormal Hb from the patient and to recycle the healthy, endogenous RBCs back to the individual. However, devices able to perform the specific separation of large volumes of RBCs into different subsets with homogenous Hb in a short period of time, at a low cost, with high purity, are not available yet. Current devices need to increase the magnetic fields and field gradient distributions in order to perform such separation. In this regard, magnetic responsive materials that can be printed using novel additive manufacturing techniques are a promising option to develop fractionators that can precisely isolate RBC subsets with equal Hb concentration each. We have demonstrated for the first time the excellent magnetic properties that magnetic responsive polymers have for cell fractionation. In this project, we will use a hybrid additive manufacturing approach to fabricate magnetic fractionators with custom magnetic field distributions based on novel magnetic inks and biocompatible microfluidic channels for a high-throughput RBC isolation into 4 subsets based on their Hb concentration. More specifically, our novel approach combines a stereolithography module for microchannel printing and a direct ink writing module for the fabrication of the magnetic field sources by varying the composition of the inks while printing. Various characterization techniques will be employed to assess the quality of the system before we use it for human RBC fractionation. Finally, this work will also strengthen our infrastructure to support undergraduate and graduate researchers and the enhancement of our biomedical engineering research environment at Texas Tech University. 1
